/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.more.util.map.bean;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import org.more.util.map.AbstractMapEntry;
/** 
 * An implementation of Map for JavaBeans which uses introspection to
 * get and put properties in the bean.
 * <p>
 * If an exception occurs during attempts to get or set a property then the
 * property is considered non existent in the Map
 *
 * @version $Revision: 812176 $ $Date: 2009-09-07 15:59:25 +0100 (Mon, 07 Sep 2009) $
 * 
 * @author James Strachan
 * @author Stephen Colebourne
 */
public class BeanMap extends AbstractMap<String, Object> implements Cloneable {
    private transient Object                        bean;
    private transient HashMap<String, Method>       readMethods      = new HashMap<String, Method>();
    private transient HashMap<String, Method>       writeMethods     = new HashMap<String, Method>();
    private transient HashMap<String, Class<?>>     types            = new HashMap<String, Class<?>>();
    /** An empty array.  Used to invoke accessors via reflection. */
    public static final Object[]                    NULL_ARGUMENTS   = {};
    /**
     * Maps primitive Class types to transformers.  The transformer
     * transform strings into the appropriate primitive wrapper.
     * N.B. private & unmodifiable replacement for the (public & static) defaultTransformers instance.
     */
    private static final Map<Class<?>, Transformer> typeTransformers = Collections.unmodifiableMap(createTypeTransformers());
    private static Map<Class<?>, Transformer> createTypeTransformers() {
        Map<Class<?>, Transformer> defaultTransformers = new HashMap<Class<?>, Transformer>();
        defaultTransformers.put(Boolean.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Boolean.valueOf(input.toString());
            }
        });
        defaultTransformers.put(Character.TYPE, new Transformer() {
            public Object transform(Object input) {
                return new Character(input.toString().charAt(0));
            }
        });
        defaultTransformers.put(Byte.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Byte.valueOf(input.toString());
            }
        });
        defaultTransformers.put(Short.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Short.valueOf(input.toString());
            }
        });
        defaultTransformers.put(Integer.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Integer.valueOf(input.toString());
            }
        });
        defaultTransformers.put(Long.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Long.valueOf(input.toString());
            }
        });
        defaultTransformers.put(Float.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Float.valueOf(input.toString());
            }
        });
        defaultTransformers.put(Double.TYPE, new Transformer() {
            public Object transform(Object input) {
                return Double.valueOf(input.toString());
            }
        });
        return defaultTransformers;
    }
    // Constructors
    //-------------------------------------------------------------------------
    /** Constructs a new empty <code>BeanMap</code>. */
    public BeanMap() {}
    /**
     * Constructs a new <code>BeanMap</code> that operates on the specified bean.
     * If the given bean is <code>null</code>, then this map will be empty.
     * @param bean  the bean for this map to operate on
     */
    public BeanMap(Object bean) {
        this.bean = bean;
        initialise();
    }
    // Map interface
    //-------------------------------------------------------------------------
    /**
     * Renders a string representation of this object.
     * @return a <code>String</code> representation of this object
     */
    public String toString() {
        return "BeanMap<" + String.valueOf(bean) + ">";
    }
    /**
     * Clone this bean map using the following process: 
     * <ul>
     * <li>If there is no underlying bean, return a cloned BeanMap without a bean.
     *
     * <li>Since there is an underlying bean, try to instantiate a new bean of
     * the same type using Class.newInstance().
     * 
     * <li>If the instantiation fails, throw a CloneNotSupportedException
     *
     * <li>Clone the bean map and set the newly instantiated bean as the
     * underlying bean for the bean map.
     *
     * <li>Copy each property that is both readable and writable from the
     * existing object to a cloned bean map.  
     *
     * <li>If anything fails along the way, throw a CloneNotSupportedException.
     * <ul>
     *
     * @return a cloned instance of this bean map
     * @throws CloneNotSupportedException if the underlying bean cannot be cloned
     */
    public Object clone() throws CloneNotSupportedException {
        BeanMap newMap = (BeanMap) super.clone();
        if (bean == null) {
            // no bean, just an empty bean map at the moment.  return a newly
            // cloned and empty bean map.
            return newMap;
        }
        Object newBean = null;
        Class<?> beanClass = bean.getClass(); // Cannot throw Exception
        try {
            newBean = beanClass.newInstance();
        } catch (Exception e) {
            // unable to instantiate
            throw new CloneNotSupportedException("Unable to instantiate the underlying bean \"" + beanClass.getName() + "\": " + e);
        }
        try {
            newMap.setBean(newBean);
        } catch (Exception exception) {
            throw new CloneNotSupportedException("Unable to set bean in the cloned bean map: " + exception);
        }
        try {
            // copy only properties that are readable and writable.  If its
            // not readable, we can't get the value from the old map.  If
            // its not writable, we can't write a value into the new map.
            Iterator<String> readableKeys = readMethods.keySet().iterator();
            while (readableKeys.hasNext()) {
                String key = readableKeys.next();
                if (getWriteMethod(key) != null) {
                    newMap.put(key, get(key));
                }
            }
        } catch (Exception exception) {
            throw new CloneNotSupportedException("Unable to copy bean values to cloned bean map: " + exception);
        }
        return newMap;
    }
    /**
     * Puts all of the writable properties from the given BeanMap into this
     * BeanMap. Read-only and Write-only properties will be ignored.
     * @param map  the BeanMap whose properties to put
     */
    public void putAllWriteable(BeanMap map) {
        Iterator<String> readableKeys = map.readMethods.keySet().iterator();
        while (readableKeys.hasNext()) {
            String key = readableKeys.next();
            if (getWriteMethod(key) != null) {
                this.put(key, map.get(key));
            }
        }
    }
    /**
     * This method reinitializes the bean map to have default values for the
     * bean's properties.  This is accomplished by constructing a new instance
     * of the bean which the map uses as its underlying data source.
     * This behavior for <code>clear()</code> differs from the Map contract in that
     * the mappings are not actually removed from the map (the mappings for a BeanMap are fixed).
     */
    public void clear() {
        if (bean == null) {
            return;
        }
        Class<?> beanClass = null;
        try {
            beanClass = bean.getClass();
            bean = beanClass.newInstance();
        } catch (Exception e) {
            throw new UnsupportedOperationException("Could not create new instance of class: " + beanClass);
        }
    }
    /**
     * Returns true if the bean defines a property with the given name. <p>
     * The given name must be a <code>String</code>; if not, this method
     * returns false. This method will also return false if the bean
     * does not define a property with that name. <p>
     * Write-only properties will not be matched as the test operates against property read methods.
     *
     * @param name  the name of the property to check
     * @return false if the given name is null or is not a <code>String</code>;
     *   false if the bean does not define a property with that name; or
     *   true if the bean does define a property with that name
     */
    public boolean containsKey(Object name) {
        Method method = getReadMethod(name);
        return method != null;
    }
    /**
     * Returns true if the bean defines a property whose current value is the given object.
     * @param value  the value to check
     * @return false  true if the bean has at least one property whose current value is that object, false otherwise
     */
    public boolean containsValue(Object value) {
        // use default implementation
        return super.containsValue(value);
    }
    /**
     * Returns the value of the bean's property with the given name. <p>
     * The given name must be a {@link String} and must not be 
     * null; otherwise, this method returns <code>null</code>.
     * If the bean defines a property with the given name, the value of
     * that property is returned.  Otherwise, <code>null</code> is returned. <p>
     * Write-only properties will not be matched as the test operates against property read methods.
     *
     * @param name  the name of the property whose value to return
     * @return the value of the property with that name
     */
    public Object get(Object name) {
        if (bean != null) {
            Method method = getReadMethod(name);
            if (method != null) {
                try {
                    return method.invoke(bean, NULL_ARGUMENTS);
                } catch (IllegalAccessException e) {
                    logWarn(e);
                } catch (IllegalArgumentException e) {
                    logWarn(e);
                } catch (InvocationTargetException e) {
                    logWarn(e);
                } catch (NullPointerException e) {
                    logWarn(e);
                }
            }
        }
        return null;
    }
    /**
     * Sets the bean property with the given name to the given value.
     * @param name  the name of the property to set
     * @param value  the value to set that property to
     * @return  the previous value of that property
     * @throws IllegalArgumentException  if the given name is null; 
     *   if the given name is not a {@link String}; if the bean doesn't
     *   define a property with that name; or if the bean property with that name is read-only
     * @throws ClassCastException if an error occurs creating the method args
     */
    public Object put(String name, Object value) throws IllegalArgumentException, ClassCastException {
        if (bean != null) {
            Object oldValue = get(name);
            Method method = getWriteMethod(name);
            if (method == null) {
                throw new IllegalArgumentException("The bean of type: " + bean.getClass().getName() + " has no property called: " + name);
            }
            try {
                Object[] arguments = createWriteMethodArguments(method, value);
                method.invoke(bean, arguments);
                Object newValue = get(name);
                firePropertyChange(name, oldValue, newValue);
            } catch (InvocationTargetException e) {
                logInfo(e);
                throw new IllegalArgumentException(e.getMessage());
            } catch (IllegalAccessException e) {
                logInfo(e);
                throw new IllegalArgumentException(e.getMessage());
            }
            return oldValue;
        }
        return null;
    }
    /**
     * Returns the number of properties defined by the bean.
     * @return  the number of properties defined by the bean
     */
    public int size() {
        return readMethods.size();
    }
    /**
     * Get the keys for this BeanMap. <p>
     * Write-only properties are <b>not</b> included in the returned set of
     * property names, although it is possible to set their value and to get their type.
     * @return BeanMap keys.  The Set returned by this method is not modifiable.
     */
    public Set<String> keySet() {
        return Collections.unmodifiableSet(readMethods.keySet());
    }
    /**
     * Gets a Set of MapEntry objects that are the mappings for this BeanMap. <p>
     * Each MapEntry can be set but not removed.
     * @return the unmodifiable set of mappings
     */
    public Set<Map.Entry<String, Object>> entrySet() {
        return Collections.unmodifiableSet(new AbstractSet<Map.Entry<String, Object>>() {
            public Iterator<Map.Entry<String, Object>> iterator() {
                return entryIterator();
            }
            public int size() {
                return BeanMap.this.readMethods.size();
            }
        });
    }
    /**
     * Returns the values for the BeanMap.
     * @return values for the BeanMap. The returned collection is not modifiable.
     */
    public Collection<Object> values() {
        ArrayList<Object> answer = new ArrayList<Object>(readMethods.size());
        for (Iterator<Object> iter = valueIterator(); iter.hasNext();) {
            answer.add(iter.next());
        }
        return Collections.unmodifiableList(answer);
    }
    // Helper methods
    //-------------------------------------------------------------------------
    /**
     * Returns the type of the property with the given name.
     * @param name  the name of the property
     * @return  the type of the property, or <code>null</code> if no such property exists
     */
    public Class<?> getType(String name) {
        return types.get(name);
    }
    /**
     * Convenience method for getting an iterator over the keys. <p>
     * Write-only properties will not be returned in the iterator.
     * @return an iterator over the keys
     */
    public Iterator<String> keyIterator() {
        return readMethods.keySet().iterator();
    }
    /**
     * Convenience method for getting an iterator over the values.
     * @return an iterator over the values
     */
    public Iterator<Object> valueIterator() {
        final Iterator<String> iter = keyIterator();
        return new Iterator<Object>() {
            public boolean hasNext() {
                return iter.hasNext();
            }
            public Object next() {
                Object key = iter.next();
                return get(key);
            }
            public void remove() {
                throw new UnsupportedOperationException("remove() not supported for BeanMap");
            }
        };
    }
    /**
     * Convenience method for getting an iterator over the entries.
     * @return an iterator over the entries
     */
    public Iterator<Map.Entry<String, Object>> entryIterator() {
        final Iterator<String> iter = keyIterator();
        return new Iterator<Map.Entry<String, Object>>() {
            public boolean hasNext() {
                return iter.hasNext();
            }
            public Map.Entry<String, Object> next() {
                String key = iter.next();
                Object value = get(key);
                return new Entry(BeanMap.this, key, value);
            }
            public void remove() {
                throw new UnsupportedOperationException("remove() not supported for BeanMap");
            }
        };
    }
    // Properties
    //-------------------------------------------------------------------------
    /**
     * Returns the bean currently being operated on.  The return value may be null if this map is empty.
     * @return the bean being operated on by this map
     */
    public Object getBean() {
        return bean;
    }
    /**
     * Sets the bean to be operated on by this map.  The given value may be null, in which case this map will be empty.
     * @param newBean  the new bean to operate on
     */
    public void setBean(Object newBean) {
        bean = newBean;
        reinitialise();
    }
    /**
     * Returns the accessor for the property with the given name.
     * @param name  the name of the property 
     * @return the accessor method for the property, or null
     */
    public Method getReadMethod(String name) {
        return (Method) readMethods.get(name);
    }
    /**
     * Returns the mutator for the property with the given name.
     * @param name  the name of the property
     * @return the mutator method for the property, or null
     */
    public Method getWriteMethod(String name) {
        return (Method) writeMethods.get(name);
    }
    // Implementation methods
    //-------------------------------------------------------------------------
    /**
     * Returns the accessor for the property with the given name.
     * @param name  the name of the property 
     * @return null if the name is null; null if the name is not a {@link String};
     *      null if no such property exists; or the accessor method for that property
     */
    protected Method getReadMethod(Object name) {
        return (Method) readMethods.get(name);
    }
    /**
     * Returns the mutator for the property with the given name.
     * @param name  the name of the 
     * @return null if the name is null; null if the name is not a {@link String};
     *      null if no such property exists; null if the property is read-only; or the mutator method for that property
     */
    protected Method getWriteMethod(Object name) {
        return (Method) writeMethods.get(name);
    }
    /** Reinitializes this bean.  Called during {@link #setBean(Object)}. Does introspection to find properties. */
    protected void reinitialise() {
        readMethods.clear();
        writeMethods.clear();
        types.clear();
        initialise();
    }
    private void initialise() {
        if (getBean() == null) {
            return;
        }
        Class<?> beanClass = getBean().getClass();
        try {
            //BeanInfo beanInfo = Introspector.getBeanInfo( bean, null );
            BeanInfo beanInfo = Introspector.getBeanInfo(beanClass);
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            if (propertyDescriptors != null) {
                for (int i = 0; i < propertyDescriptors.length; i++) {
                    PropertyDescriptor propertyDescriptor = propertyDescriptors[i];
                    if (propertyDescriptor != null) {
                        String name = propertyDescriptor.getName();
                        Method readMethod = propertyDescriptor.getReadMethod();
                        Method writeMethod = propertyDescriptor.getWriteMethod();
                        Class<?> aType = propertyDescriptor.getPropertyType();
                        if (readMethod != null) {
                            readMethods.put(name, readMethod);
                        }
                        if (writeMethod != null) {
                            writeMethods.put(name, writeMethod);
                        }
                        types.put(name, aType);
                    }
                }
            }
        } catch (IntrospectionException e) {
            logWarn(e);
        }
    }
    /**
     * Called during a successful {@link #put(Object,Object)} operation.
     * Default implementation does nothing.  Override to be notified of
     * property changes in the bean caused by this map.
     *
     * @param key  the name of the property that changed
     * @param oldValue  the old value for that property
     * @param newValue  the new value for that property
     */
    protected void firePropertyChange(Object key, Object oldValue, Object newValue) {}
    // Implementation classes
    //-------------------------------------------------------------------------
    /** Map entry used by {@link BeanMap}. */
    protected static class Entry extends AbstractMapEntry<String, Object> {
        private BeanMap owner;
        /**
         * Constructs a new <code>Entry</code>.
         * @param owner  the BeanMap this entry belongs to
         * @param key  the key for this entry
         * @param value  the value for this entry
         */
        protected Entry(BeanMap owner, String key, Object value) {
            super(key, value);
            this.owner = owner;
        }
        /**
         * Sets the value.
         * @param value  the new value for the entry
         * @return the old value for the entry
         */
        public Object setValue(Object value) {
            String key = getKey();
            Object oldValue = owner.get(key);
            owner.put(key, value);
            super.value = owner.get(key);
            return oldValue;
        }
    }
    /**
     * Creates an array of parameters to pass to the given mutator method.
     * If the given object is not the right type to pass to the method 
     * directly, it will be converted using {@link #convertType(Class,Object)}.
     *
     * @param method  the mutator method
     * @param value  the value to pass to the mutator method
     * @return an array containing one object that is either the given value or a transformed value
     * @throws IllegalAccessException if {@link #convertType(Class,Object)} raises it
     * @throws IllegalArgumentException if any other exception is raised by {@link #convertType(Class,Object)}
     * @throws ClassCastException if an error occurs creating the method args
     */
    protected Object[] createWriteMethodArguments(Method method, Object value) throws IllegalAccessException, ClassCastException {
        try {
            if (value != null) {
                Class<?>[] types = method.getParameterTypes();
                if (types != null && types.length > 0) {
                    Class<?> paramType = types[0];
                    if (!paramType.isAssignableFrom(value.getClass())) {
                        value = convertType(paramType, value);
                    }
                }
            }
            Object[] answer = { value };
            return answer;
        } catch (InvocationTargetException e) {
            logInfo(e);
            throw new IllegalArgumentException(e.getMessage());
        } catch (InstantiationException e) {
            logInfo(e);
            throw new IllegalArgumentException(e.getMessage());
        }
    }
    /**
     * Converts the given value to the given type.  First, reflection is
     * is used to find a public constructor declared by the given class 
     * that takes one argument, which must be the precise type of the 
     * given value.  If such a constructor is found, a new object is
     * created by passing the given value to that constructor, and the
     * newly constructed object is returned.<P>
     *
     * If no such constructor exists, and the given type is a primitive
     * type, then the given value is converted to a string using its 
     * {@link Object#toString() toString()} method, and that string is
     * parsed into the correct primitive type using, for instance, 
     * {@link Integer#valueOf(String)} to convert the string into an
     * <code>int</code>.<P>
     *
     * If no special constructor exists and the given type is not a 
     * primitive type, this method returns the original value.
     *
     * @param newType  the type to convert the value to
     * @param value  the value to convert
     * @return the converted value
     * @throws NumberFormatException if newType is a primitive type, and 
     *  the string representation of the given value cannot be converted to that type
     * @throws InstantiationException  if the constructor found with 
     *  reflection raises it
     * @throws InvocationTargetException  if the constructor found with
     *  reflection raises it
     * @throws IllegalAccessException  never
     * @throws IllegalArgumentException  never
     */
    protected Object convertType(Class<?> newType, Object value) throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
        // try call constructor
        Class<?>[] types = { value.getClass() };
        try {
            Constructor<?> constructor = newType.getConstructor(types);
            Object[] arguments = { value };
            return constructor.newInstance(arguments);
        } catch (NoSuchMethodException e) {
            // try using the transformers
            Transformer transformer = getTypeTransformer(newType);
            if (transformer != null) {
                return transformer.transform(value);
            }
            return value;
        }
    }
    /**
     * Returns a transformer for the given primitive type.
     *
     * @param aType  the primitive type whose transformer to return
     * @return a transformer that will convert strings into that type,
     *  or null if the given type is not a primitive type
     */
    protected Transformer getTypeTransformer(Class<?> aType) {
        return (Transformer) typeTransformers.get(aType);
    }
    /**
     * Logs the given exception to <code>System.out</code>.  Used to display
     * warnings while accessing/mutating the bean.
     *
     * @param ex  the exception to log
     */
    protected void logInfo(Exception ex) {
        // Deliberately do not use LOG4J or Commons Logging to avoid dependencies
        System.out.println("INFO: Exception: " + ex);
    }
    /**
     * Logs the given exception to <code>System.err</code>.  Used to display
     * errors while accessing/mutating the bean.
     *
     * @param ex  the exception to log
     */
    protected void logWarn(Exception ex) {
        // Deliberately do not use LOG4J or Commons Logging to avoid dependencies
        System.out.println("WARN: Exception: " + ex);
        ex.printStackTrace();
    }
}
